You cannot change PBO name. It doesn't work like this. You have to extract the contents of the PBO is like a zip file but BIS's way of packing everything up into one file. You will then see .Altis, .Tanoa or whatever map it is as a folder.

From here you can change .XXX to the proper name of the map you want to use. I don't know exactly what Chernarus map name actually is.

Then you have to open the map in Eden and move all the stores, mission markers and everything else in the right places.

As for using @Cup stuff its not a serverside mod, its a client side so clients must have it. The -serverMod parameter means only the server needs the mod, not clients.

Its not simple as you think but its simple once you understand what you have to do. It actually takes me about 2 weeks to convert a map to Wasteland if I work on here and there. I've converted 2 maps so far, Australia and Taunus but Taunus was a failure due to the map itself having way too many bugs in it. Australia is a good map but its huge and doesn't have a lot of forests which is lacking IMHO.